Noncovalent Cross-Linking of Casein by Epigallocatechin Gallate Characterized by Single Molecule Force Microscopy

Abstract

Interaction of the tea polyphenol epigallocatechin gallate (EGCG) with beta-casein in milk affects the taste of tea and also affects the stability of the tea and the antioxidant ability of the EGCG. In addition, interaction of polyphenols with the chemically similar salivary proline-rich proteins is largely responsible for the astringency of tea and red wine. With the use of single molecule force microscopy, we demonstrate that the interaction of EGCG with a single casein molecule is multivalent and leads to reduction in the persistence length of casein as calculated using the wormlike chain model and a reduction in its radius of gyration. The extra force required to stretch casein in the presence of EGCG is largely entropic, suggesting that multivalent hydrophobic interactions cause a compaction of the casein micelle.

Nettle (Urtica dioica L.) extracts as functional ingredients for production of chocolates with improved bioactive composition and sensory properties

“…Namely, previous studies (Galmarini et al 2013) have reported about the significant decrease in the content of catechins during storage. The observed fluctuations can also be attributed to the presence of sugars, polysaccharides and proteins in the chocolates, since polyphenols can bind with proteins and peptides forming soluble and insoluble complexes through hydrophobic interaction and hydrogen bonding (Jobstl et al 2006), which may interfere during analytical determination. According to Jobstl et al (2006) polyphenols also have the ability to bind to iron and reduce its availability.…”

“…The observed fluctuations can also be attributed to the presence of sugars, polysaccharides and proteins in the chocolates, since polyphenols can bind with proteins and peptides forming soluble and insoluble complexes through hydrophobic interaction and hydrogen bonding (Jobstl et al 2006), which may interfere during analytical determination. According to Jobstl et al (2006) polyphenols also have the ability to bind to iron and reduce its availability. Nettle leaves were noted for their particularly high content of some metals (Se, Zn and Fe, Mg) (Rzemykowska and Ostrowska 1994).…”

Epigallocatechin Gallate Inactivates Clinical Isolates of Herpes Simplex Virus

“…In fact, tea, and therefore EGCG, is on the FDA's list of compounds generally recognized as safe and approved for human consumption (34). EGCG binds to a wide variety of proteins, especially to nonglobular extended proteins and particularly to proteins with a high proline content (10,11,18,24,31,33,37,44). EGCG inhibits the binding of HIV envelope glycoprotein gp120 to the CD4 receptor (15,20,52) and inhibits influenza virus replication by specific interaction with the hemagglutinin envelope glycoprotein and potentially altering the physical properties of the viral envelope (29,40).…”

Gallated Form of Tea Catechin, Not Nongallated Form, Increases Fecal Starch Excretion in Rats

“…Bajerska et al (19) also reported that supplementation with 1.1% green tea extract reduced the apparent digestion of protein. Provided that EGCG interacts with proteins (20), one explanation for a reduction of apparent digestibility of protein may be that EGCG directly bound to dietary casein, or more specifically that EGCG bound to the proteinhydrolyzing enzymes in the intestinal tract. However, it remains unclear whether tea catechins influence a secretion of endogenous proteins and/or reabsorption of endogenously secreted proteins.…”